While certain bio-behavioral relationships have been extensively studied in impulsive aggression (e.g. brain serotonin), structural MRI studies have not yet been performed among individuals with recurrent, problematic impulsive aggression. The aim of this study is to collect data concerning specific brain regions that may be involved in impulsive aggression. Neuroimaging data will be collected from subjects who meet diagnostic criteria for Intermittent Explosive Disorder (IED) and from non-psychiatric control subjects. High-resolution Magnetic Resonance Imaging methods will be used to determine whether specific regions of interest are reduced or altered in the brains of impulsive aggressive subjects. Specifically, volumetric measures will be derived for orbital and dorsolateral prefrontal areas and for the amygdala. Whole brain and hemispheric volumes will also be evaluated. Neuroimaging data will be evaluated in the context of other laboratory and personality variables. Select laboratory tasks will be used to evaluate IED subjects for evidence of cognitive impairment involving prefrontal and amygdalar function. In addition, individual differences in impulsivity and aggression will also be quantified using various validated psychometric instruments. This information will be used to identify anatomic and cognitive correlates of the severity of impulsivity and aggression, respectively. The presence or absence of structural brain abnormalities is relevant to an understanding of the etiology of impulsive aggression. Data obtained in this study will yield findings regarding brain structures potentially involved in impulsive aggression and provide insights concerning etiological factors in Intermittent Explosive Disorder.